As a resin composition including an oxyalkylene polymer and an acrylic polymer, for example, a curable urethane composition including a polyetherpolyol, an acrylic polyol, and a polyisocyanate compound and a curable composition, which can be used as a solventless contact adhesive, including a hydrolyzable silicon group-containing oxyalkylene polymer and a hydrolyzable silicon group-containing acrylic polymer are known, the curable composition being disclosed in Japanese Unexamined Patent Application Publication No. 3-263478 and Japanese Unexamined Patent Application Publication No. 7-258536.
With respect to the oxyalkylene polymer used in such a resin composition, an oxyalkylene polymer prepared by ring-opening polymerization of an alkylene oxide in the presence of a cobalt-containing double metal cyanide complex catalyst can have a number-average molecular weight of 8,000 or more with narrow molecular-weight distribution and is advantageous from the standpoint of the flexibility of a cured product prepared from the curable resin composition, viscosity of the composition, and workability. With respect to the acrylic polymer, an acrylic polymer prepared by radical polymerization in the presence of a mercapto group-containing compound is advantageous in easy adjustment of the molecular weight, compatibility with the oxyalkylene polymer in the resin composition, and the adjustment of the viscosity of the composition. The mercapto group-containing compound can be added to a composition in order to modify, for example, an unsaturated group-containing oxyalkylene polymer and a curable urethane composition, and to adjust the curability of a curable composition containing a hydrolyzable silicon group.
However, a resin composition including an oxyalkylene polymer prepared by the above-described specific production process and an acrylic polymer prepared by the above-described specific production process and/or a mercapto group-containing compound is excessively colored, in particular, red-colored. Thereby, the appearance of a cured product produced from the resin composition or the curable resin composition may be significantly impaired. This coloration is particularly disadvantageous, for example, when the resin composition is used as a transparent composition, in particular, as a transparent adhesive for bonding a transparent component, and when a specific-colored composition is required, in particular, when a light color, such as white or beige, is required.